1. Field of the Invention
This invention relates to well completion and more particularly to method and apparatus for sand packing both the formation to be produced and the annulus between the perforated well casing and a screen liner hung inside the casing by means of a hookwall packer.
2. Certain Prior Art
It is known to effect the foregoing objective with a screen liner assembly including a main screen and a telltale screen therebelow, using a sand placement tool including a length of dual flow passage pipe releasably set inside the well packer to provide for dual flow past the packer. A tailpipe connected to the lower end of the inner tube of the dual pipe and sealed to the liner above and below the main screen prevents flow through the main screen into the annulus between the tail pipe and main screen. A cross-over connecting the upper end of the dual pipe to the tubing diverts tubing flow to the outer flow passage of the dual pipe. Flow is then out the side of the dual pipe, through the packer mandrel below its seal rings, and thence to the casing-line annulus. The tail pipe connected to the lower end of the dual pipe receives liquid returning from the casing-liner annulus through the tell-tale screen below the main or lower screen and delivers the fluid to the inner tube of the dual pipe, which conducts the fluid via the cross over to the casing-tubing annulus. A valve in the cross over can be closed to block such return flow.
With the valve open, sand slurry is delivered from the tubing via the cross-over to the top of the casing-liner annulus. The bottom of the casing-liner annulus is closed by the bottom of the well or a packer. The sand is delivered in a manner to build up sand in the annulus from the bottom of the annulus to the top in between the main screen and casing. The liquid portion of the slurry returns to the tool through the tell-tale screen, which filters out the sand. The liquid exits the tool to the casing-tubing annulus via the cross-over.
After a certain amount of sand is built up in the casing-liner annulus, the cross-over valve is closed so that further slurry is forced into the formation, and to some extent water is squeezed out of the annulus sand into the formation so that the annulus sand is compacted.
Thereafter, the tool is lifted out of the liner, the cross-over valve is opened, and the tool is flushed by reverse circulation. The tool is then withdrawn from the well, following which production tubing is run into the well. A seal tube at the lower end of the tubing is installed in the mandrel of the retrievable permanent packer supporting the screen liner. Such a system is exemplified by the disclosure in the brochure entitled:
"OTIS SINGLE--ZONE SAND-CONTROL SYSTEM"
published by Otis Engineering Corporation and identified as 6865-3M-10/78.